The Love Bug virus could cost companies and consumers worldwide as much as $10bn.

Why would anyone go to the effort of writing something so destructive?

"It is similar to asking why people hack," said Brian Martin, who works for the security website Attrition.org.

"Some virus creators do it for pure creativity, to see how tight they can get the code, how efficient it can be, how well they can hide it," he said.

But most virus writers who do it for the technical challenge do not release their viruses into the wild, he added. Instead, they simply share their code with other virus writers.

They want their ability to be recognised by their peers.

The need to be noticed

But there is a darker side to this need for recognition.
Celebrated former hacker Kevin Poulsen believes the evidence points to an ego-driven young person as having been responsible for the Love Bug virus.

The elements of cleverness, sinister sneakiness and subterfuge in such an attack appeal to a young person, he told the BBC.

This kind of attack is ego-driven

Kevin Poulsen

And he should know - he was only 17 when he hacked into the US Department of Defense's Arpanet.

He later spent five years in jail for other computer crimes.

"If you are at all in touch with your juvenile delinquent side, it is not hard to see how this might appeal to a kid to be able to write 30 to 40 lines of code and make news all around the world," said Mr Poulsen, editorial director of SecurityFocus.com.

There is disagreement among experts about what level of expertise was needed to
write the Love Bug virus.

Mr Poulson said that the Love Bug virus took more sophistication than the attacks that brought down several high-profile websites in February.

In that attack, hackers downloaded a readily available programme on the internet and installed it on vulnerable computers.

He says it is a myth perpetuated by the media that writing a "worm" - a self-replicating virus - like the Love Bug takes any intelligence or talent.

"All they had to do was download a virus kit. There is very little intelligence in that," he said. "They are simply satisfying their sick need for significance," said the former National Security Agency staffer.

He said that the media wrongly assumes that if this virus can create such wide spread damage that the writer must be brilliant.

"Hackers thrive on that. It is so easy, but they get so much respect for brain-dead damaging things, which aren't work of geniuses," he said.

No idea of damage

Indeed, Mr Poulsen and Mr Martin said that the virus writer probably had no idea of the kind of damage that would be unleashed on the internet.

It wouldn't surprise me if they were sitting in shock, amazed at the damage done

Brian Martin, Attrition.org

Mr Poulsen pointed to the example of the first major virus on the internet, the Morris worm.

It infected an estimated 10% of the computers on the internet in 1988.

Robert Morris, then a 23-year-old graduate student, wrote the virus and unleashed it from an MIT computer lab.

The worm was only supposed to place one copy of itself on each computer, but Morris made a mistake. It copied itself over and over again, flooding the internet.

With the Love Bug virus, Mr Martin said, "it wouldn't surprise me if they were sitting in shock, amazed at the damage done."